FCC separation method and apparatus with improved stripping

Claim 1

An FCC process for the fluidized catalytic cracking of a hydrocarbon feedstock comprising: passing a hydrocarbon feedstock and solid catalyst particles into a riser conversion zone comprising a conduit to produce a mixture of solid particles and gaseous fluids; passing said mixture of said catalyst particles and gaseous fluids into a separation vessel through said conduit wherein said conduit occupies a central portion of said separation vessel and said separation vessel is located within a reactor vessel; tangentially discharging said mixture from said conduit through a discharge opening into said separation vessel; passing catalyst particles into a first catalyst bed located in a lower portion of said separation vessel and contacting said catalyst particles with a first stripping gas in said first bed; passing said catalyst particles from said first bed into a second bed located in said separation vessel below said first catalyst bed, contacting said catalyst particles with a second stripping gas and passing said second stripping gas into said first catalyst bed to supply a portion of said first stripping gas; passing said catalyst particles from said second bed to a stripping zone, contacting said particles with a third stripping gas in said stripping zone and passing said third stripping gas into said second catalyst bed to supply at least a portion of said second stripping gas; passing a purge medium into an upper portion of said reactor vessel; passing at least a portion of said purge medium through a plurality of restricted openings arranged circumferentially around the outside said separation vessel at the bottom of said first catalyst bed to supply a portion of said first stripping gas; recovering stripped catalyst particles from said stripping zone; and, collecting gaseous fluids including said first stripping gas and catalyst particles from an upper portion of said separation vessel into an outlet and withdrawing gaseous fluids from said separation vessel for recovery.